Although many teachers have had an enduring and positive influence on their students, some teachers' behavior is unprofessional, contributing to youngsters' alienation and reinforcing negative public opinion about the teaching profession. This field study describes various defensive maneuvers, strategies, and pranks that teachers devised and relied on to get through the school year at a midwestern high school. Using a natural history/direct observation approach, a 7-month field study targeting the social studies department of "Roosevelt High School" (a fictitious name for a real school in the midwest) was conducted during 1980-81. This report summarizes study results and focuses on two primary informants representative of the 14 real teachers whose teaching concepts, jokes, likes, and dislikes were sought out continuously. Field workers participated in many out-of-class activities with these teachers and made notes when appropriate. The study disclosed two rival cliques of teachers who treated subject matter, classrooms, the gym, and the professional library as territories to be defended. Each informal group developed strategies for protecting whatever subject matter territory they possessed and laid plans for looting this territory from the other clique. Teachers also devised bulwarks against looting, "raping," and raising general havoc by others within and outside the department. Results are inconsistent with other research findings about teacher collegiality. The informal groups were teachers' response to fatigue, frustration, and distrust resulting from their lowly position in the school hierarchy. Unfortunately, this conduct is unbefitting a professional. Included are 14 references. (MLH)